Tsukuba, Japan
Tsukuba, Japan

Time filter

Source Type

Miwa K.,BEANS Laboratory | Nishimori Y.,BEANS Laboratory | Ueki S.,BEANS Laboratory | Sugiyama M.,University of Tokyo | And 2 more authors.
Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures | Year: 2013

A low-damage silicon etching technology for fabricating microelectromechanical system (MEMS) devices using a neutral beam is reported. Neutral beams were produced from Cl2 plasma in an etching apparatus and were used to etch silicon trenches and MEMS devices. Si trench etch rate depended on the bias voltage applied to an aperture, used to produce the neutral beam. Etch rate decreased with increasing Si trench aspect ratio. This trend was minimized by enlarging the aspect ratio of through-holes in the aperture. The silicon trench profile was influenced by the aspect ratio of through-holes in the aperture. Etched Si surfaces were smooth, and no damage/defects were observed by transmission electron microscopy. Si etching of MEMS devices with smooth surfaces and scallop free sidewalls was achieved. The mechanical characteristics of an oscillator etched with the neutral beam were superior to those of that etched using a conventional Bosch process. © 2013 American Vacuum Society.


Takamatsu S.,Tokyo University of Information Sciences | Takamatsu S.,BEANS Laboratory | Takahata T.,Tokyo University of Information Sciences | Matsumoto K.,Tokyo University of Information Sciences | Shimoyama I.,Tokyo University of Information Sciences
Journal of Micromechanics and Microengineering | Year: 2011

We have developed a process to pattern the conductive polymer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film and the insulation polymer of the perfluoro polymer (Cytop) with a Parylene lift-off method for the purpose of fabricating a PEDOT:PSS-based electrochromic display device. Because conventional micro-patterning processes decrease the conductivity of organic electronic polymers due to the destructive solutions of photolithography, PEDOT:PSS and Cytop polymers were patterned by using the dry lift-off film of Parylene. Its patterning resolution of PEDOT:PSS was found to be as low as 20 μm. The insulation layer of Cytop was also patterned on the PEDOT:PSS pattern with the same resolution. This process was able to pattern the 300 μm wide wiring and 1 mm square pixels of PEDOT:PSS and the Cytop to cover the entire area except for the pixels constructed to form an electrochromic display. Finally, the fabricated 4 × 4 pixel device displayed a simple shape, a transverse line. © 2011 IOP Publishing Ltd.


Li Y.F.,BEANS Laboratory | Tomizawa Y.,BEANS Laboratory | Koga A.,Toshiba Corporation | Hashiguchi G.,University of Shizuoka | And 2 more authors.
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2011

A novel trench-type anti-wear microprobe with nano-scale electric contacts was proposed as an AFM probe to overcome the problem of probe tip wear and improve patterning stability in Atomic force microscope (AFM) local anodic oxidation (LAO) lithography. The proposed microprobe was fabricated using MEMS technique. The patterning and wear properties of the fabricated microprobe in AFM LAO lithography were investigated in terms of the change in the drawn line width and probe tip shape before and after a 20 mm scan. SEM images of the probe tips before and after the scan indicated that there was no obvious damage in the fabricated probe tip while apparent damage could be found on the conventional type probe tip. AFM LAO lithography results showed that the fabricated microprobe maintained a stable pattering performance before and after the 20 mm scan while the conventional type probe was unable to draw due to tip wear after the scan.


Yamashita T.,University of Tokyo | Yamashita T.,BEANS Laboratory | Itoh T.,Japan National Institute of Advanced Industrial Science and Technology | Suga T.,University of Tokyo
Journal of Japan Institute of Electronics Packaging | Year: 2012

An anti-stiction coating with a self-assembled monolayer (SAM) was investigated for ohmic contact micro-electro-mechanical system (MEMS) switches with low-load contacts. SAMs of thiophenol (TP) or 2-naphthalenethiol (2-NT) were coated on Au samples with variations in surface roughness to investigate the effects of the surface asperities on the adhesion force. The adhesion force was measured using a silicon tipless cantilever in the relative humidity range of 10 to 85% for the SAM coated samples and compared with those for the Au and SiO2 sample surfaces. The adhesion force measurements indicate that the TP and 2-NT coatings can prevent a liquid meniscus from forming on the device surfaces due to their hydrophobic character caused by the protruding aromatic group. In addition, it was confirmed that these coatings could reduce van der Waals forces more than the Au coating. Based on these results, SAMs of TP and 2-NT have excellent potential as anti-stiction coatings for MEMS switch contacts.


Imai T.,BEANS Laboratory | Takamatsu S.,BEANS Laboratory | Takamatsu S.,Japan National Institute of Advanced Industrial Science and Technology | Shiraishi K.,University of Tsukuba | And 3 more authors.
Procedia Engineering | Year: 2012

We applied die-coating process to making thin films on plastic-tape substrates in order to enable continuous, high speed fabrication for textile integration. A high coating speed of 20 m/min was successfully attained in the formation of regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM) and poly(3,4- ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) layers on polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates, for the first time to the best of our knowledge. In order to confirm that those layers can be applied to devices, we fabricated PET/ITO/PEDOT:PSS/P3HT:PCBM/Al photovoltaic thin-film devices (width: 5 mm). Film was woven at an interval of 7 mm to form the sheet sample with the dimension of 120 mm × 120 mm. Current-voltage (I-V) characteristics of the active part of the devices were confirmed. © 2012 The Authors. Published by Elsevier Ltd.


Takamatsu S.,BEANS Laboratory | Kobayashi T.,Japan National Institute of Advanced Industrial Science and Technology | Shibayama N.,BEANS Laboratory | Miyake K.,Japan National Institute of Advanced Industrial Science and Technology | And 2 more authors.
Sensors and Actuators, A: Physical | Year: 2012

We report on the fabrication and characterization of a large area (handkerchief-size, i.e., >16 cm × 16 cm) of pressure sensor fabric. The sensor is constructed by weaving the fibers, which are coated with the organic conductive polymer poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) and a dielectric film of perfluoropolymer (Cytop), and the capacitances at the points of the crossed fibers vary with the applied force. The functional films are continuously coated with die-coating system with the thickness ranging from hundreds nm to several μm. The resultant fibers are loomed, forming the sensor fabric with an area of 16 cm × 16 cm. Its sensitivity ranged from 0.98 to 9.8 N/cm 2, which is within the range of human touch. Therefore, our fabric touch sensors could lead to applications from wearable keyboards to sensors embedded in beds for health care purposes. © 2012 Elsevier B.V. All rights reserved.


Takamatsu S.,Japan National Institute of Advanced Industrial Science and Technology | Takamatsu S.,BEANS Laboratory | Kurihara K.,Japan National Institute of Advanced Industrial Science and Technology | Yamashita T.,Japan National Institute of Advanced Industrial Science and Technology | And 3 more authors.
Journal of Micromechanics and Microengineering | Year: 2014

We have developed a simple micro-patterning process for high conductive polymer (i.e., poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)) with a patterned substrate by using an ultraviolet (UV) nano-imprint and an ethylene glycol-based second doping technique. In the patterning process, the PEDOT:PSS water dispersion is first coated only on the hydrophilic area, which is fabricated by UV nano-imprinting, forming patterned PEDOT:PSS on the substrate. The patterned PEDOT:PSS film is then immersed in the ethylene glycol as a second doping technique for increasing its conductivity. The proposed process provides simplicity in terms of shorter process steps of the UV nano-imprinting and PEDOT:PSS coating and higher conductivity of patterned PEDOT:PSS film than existing complicated micro-fabrication processes for organic materials. The 200 nm wide nano-imprinted pillar structures change the wettability of the substrate where the contact angle of the substrate is decreased from 66.8° to 33.3°. The patterning resolution with the nano-imprinted pattern substrate is down to 100 m, which is useful for sensor applications. The conductivity increase delivers a low sheet resistance (120 Ω sq-1) of patterned PEDOT:PSS film. Then, the patterning of PEDOT:PSS sensor shapes with its 300 m wide feature line and high conductivity are demonstrated. Therefore, our process leads to applications to a variety of PEDOT:PSS-based sensors. © 2014 IOP Publishing Ltd.


Takamatsu S.,Japan National Institute of Advanced Industrial Science and Technology | Takamatsu S.,BEANS Laboratory | Yamashita T.,Japan National Institute of Advanced Industrial Science and Technology | Yamashita T.,BEANS Laboratory | And 3 more authors.
Sensors and Actuators, A: Physical | Year: 2014

We developed a lightweight flexible keyboard with a touch sensor fabric that consists of conductive polymer-coated fibers. In our sensor fabric, the conductive polymer-coated fibers, which are sensing electrodes, are woven at a 2-cm pitch and the rest of the fabric is filled with pristine polyester fibers. The sensing principle for human touch detection is the measurement of the capacitance between the conductive polymer-coated sensing fibers and human fingers. The keyboard system consists of the touch sensor fabric, a capacitance measurement circuit, a signal processing circuit and software for entering characters into a personal computer (PC). The fabricated fabric has a large area, 20.5 cm × 12.5 cm, and weighs only 9 g, making it large enough for touch input and light enough to carry. In addition, the sensing electrode is bendable to a diameter of 1 mm because the sensor electrode is not inorganic material but rather polymer. When the sensor is touched, the capacitance between fiber and finger is increased by 2 pF, which is large enough to be detected with conventional capacitance measurement circuits. Finally, the keyboard input is demonstrated with our fabricated fabric sensors. This technology will lead to the development of keyboards that are especially well suited for wearable and portable electronic devices. © 2014 Elsevier B.V. All rights reserved.


Takamatsu S.,BEANS Laboratory | Kurihara K.,Japan National Institute of Advanced Industrial Science and Technology | Imai T.,BEANS Laboratory | Yamashita T.,BEANS Laboratory | And 2 more authors.
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2012

We reports on a new patterning technique of conjugated polymer (i.e., PEDOT:PSS) with high conductivity which consists of UV-nanoimprinted surface modified substrate and second doping with ethylene glycol. Generally, organic conjugated polymers are very weak to standard photolithography because alcohol or high temperature treatment decreases conductivity of the polymers. Therefore, we proposed new fabrication process where firstly hydrophilic surface is patterned on plastic substrates with UV nano-imprint, PEDOT:PSS water-dispersion is patterned only on the hydrophilic area, then PEDOT:PSS is doped with ethylene glycol for increasing its conductivity. This process is just operated under room temperature and without alcohol and second doping is also produced, which lead to high conductivity of PEDOT:PSS. © 2012 IEEE.


Yamashita T.,BEANS Laboratory | Miyake K.,BEANS Laboratory | Miyake K.,Japan National Institute of Advanced Industrial Science and Technology | Itoh T.,BEANS Laboratory | Itoh T.,Japan National Institute of Advanced Industrial Science and Technology
DTIP 2012 - Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS | Year: 2012

This paper presents an innovation and fabrication process of electrical contact structure in flexible device technology. A coating of poly(3,4-ethylenedioxythiophene) poly(4-styrenesulfonate) as a solid electrolytic layer deposited on silicone elastomer structure is employed in composing the electrical circuit through a large area of woven electronic textile (e-textile), and functions as the electrical contact between weft and warp (interlaced) fiber ribbons. From the resistance measurements using flexible sheets by weaving polyethylene terephthalate ribbon cable, the structure enhances the durability, flexibility and stability of electrical contact in the woven e-textile better than those of the ribbons without it. © 2012 CMP.

Loading BEANS Laboratory collaborators
Loading BEANS Laboratory collaborators